THE Independent Commission Against Corruption (ICAC) allowed Alex Tsui Ka-kit to maintain in total secrecy a private file on an informant. ICAC Commissioner Bertrand de Speville told the security-panel hearing yesterday that the file created for the former deputy director of operations to keep records of his contacts with Henfrey Tin - an ''undesirable character'' - had not been retained under the authority of another officer. Mr de Speville conceded it was ''unusual'' for an officer of Mr Tsui's rank to have dealings with informants. But, despite the sensitivity of the contact and the special circumstances under which it was sanctioned, no ICAC official had access to the file and it was not subject to an annual review. All other records used by the ICAC to verify the probity of officer-informer relationships are regularly examined. Mr de Speville told legislators that normal ICAC regulations did not apply to Mr Tsui's special contact. It was ''a very unusual situation'', he said in response to questions from United Democrat legislator Martin Lee Chu-ming on the second day of the inquiry into Mr Tsui's sacking. ''It wasn't a normal informants file where the details of the informant - the identity of the informant - is kept quite separate from the file and is kept by another officer, a principal investigator,'' he said. ''These regulations that you see here - the requirement for an annual review - applies to the file when it is opened in a normal, regular way. ''Namely, you have the principal investigator with a number of informant particulars in his safe and he calls for the informers' files which are in his group and sees what the position is. ''Here, it was different because it was Mr Tsui himself at assistant-director level who had the information about the informer and the record of contacts with the informer with him on the same file. ''Nobody else had access to that file though the Deputy Director and the Director of Operations had seen the file and indeed had noted each of the entries made in it. But there was no annual review of that file.'' In his evidence yesterday, Mr de Speville revealed also that he believed there was nothing wrong with ICAC officers maintaining private affiliations. ''They are not obliged to report the fact that they have joined a particular group or a particular organisation,'' he said. ''It is the whole of our code of ethic that officers must be careful about contacts. Their responsibilities as ICAC officers do not cease once they walk out of the office.'' In previous testimony, it was heard Mr Tsui was given top-level permission to reopen a relationship with Mr Tin, as an informant, because of the potential intelligence of such an association. This meant every contact with Mr Tin had to be recorded. But between January, 1990 and March, 1991, only four meetings were noted in the file. One day after Mr Tsui applied to open the file, information was received by the ICAC from an informant to suggest Mr Tin and another man, Hung Hing-wah, were involved in a cigarette smuggling racket. Mr Hung is the president of the Hong Kong Boxing Association. Mr Tin is a vice-president. Both men are on ICAC bail and possibly face charges in relation to cigarette smuggling. Mr Tsui is also a senior member of the association. Yesterday, Mr Tsui defended his relationship with Mr Tin and rejected claims Mr Tin was a ''paid informant''. He denied that an official memo he submitted in 1990, about the honest nature of a business operated by Mr Hung, was designed to sidetrack an ICAC investigation into cigarette smuggling. ''He [Mr Tin] was definitely not a paid informant,'' he said. ''If you called him that it would be an insult to him.''